The bytecode application is a program in the execution format, obtained by compiling the class structure described with use of the source code of the object-oriented programming language. The bytecode application is composed of codes that do not depend on the machine (bytecodes). The playback devices in recent years have succeeded in enhancing the added value of the playback device or a content, by causing the bytecode application to execute not only the playback control for playing back the content, but an interactive control or an additional control.
One of the functions that are to be implemented in the playback device as the functions used by the bytecode applications is a copy function, which is recited in the following patent literature.